AlNAC4 Transcription Factor From Halophyte Mitigates Oxidative Stress by Maintaining ROS Homeostasis in Transgenic Tobacco.

NAC proteins are a large family of plant-specific transcription factors which regulate both ABA-dependent and -independent gene expression. These transcription factors participate in biotic and abiotic stress-response through intricate regulation at transcriptional, post-transcriptional and post-translational levels. In the present study, AlNAC4 transcription factor was isolated from a salt excreting halophyte . The has an open reading frame of 936 bp, encoding a protein of 312 amino acid, with an estimated molecular mass of 34.9 kDa. The showed close homology to monocot NACs in the phylogenetic tree. analysis revealed that AlNAC4 possess the characteristic A-E subdomains within the NAC domain. The AlNAC4 showed sixteen post-translational phosphorylation sites. The transcript was significantly upregulated with dehydration and HO treatments, showing its role in osmotic and oxidative stress, respectively. The recombinant protein showed binding to mono as well as tandem repeats of NAC recognition sequence (NACRS) of the promoter. This is the first report mentioning that overexpression of improved oxidative stress tolerance in tobacco transgenics. The transgenics maintained ROS homeostasis during HO treatment. The transgenics showed regulation of stress-responsive genes including , , , , and transcription factors like , during oxidative stress. The AlNAC4 transcription factor from recretohalophyte Aeluropus showed regulation with abiotic stresses and binding to NACRS elements of promoter. The tobacco transgenics showed improved growth with oxidative stress.